Python:将函数应用于嵌套字典中的值 [英] Python: Apply function to values in nested dictionary

问题描述

我有一组任意深的嵌套字典:

I have an arbitrarily deep set of nested dictionary:

x = {'a': 1, 'b': {'c': 6, 'd': 7, 'g': {'h': 3, 'i': 9}}, 'e': {'f': 3}}

我想基本上将一个函数应用于字典中的所有整数，所以我想像map一样，但是对于嵌套字典.

and I'd like to basically apply a function to all the integers in the dictionaries, so like map, I guess, but for nested dictionaries.

所以:map_nested_dicts(x, lambda v: v + 7)是目标.

我坚持最好的方法来存储键层，然后将修改后的值放回正确的位置.

I'm stuck as to the best way to perhaps store the layers of keys to then put the modified value back into its correct position.

做到这一点的最佳方法/方法是什么?

What would the best way/approach to do this be?

推荐答案

以递归方式访问所有嵌套值:

Visit all nested values recursively:

import collections

def map_nested_dicts(ob, func):
    if isinstance(ob, collections.Mapping):
        return {k: map_nested_dicts(v, func) for k, v in ob.iteritems()}
    else:
        return func(ob)

map_nested_dicts(x, lambda v: v + 7)
# Creates a new dict object:
#    {'a': 8, 'b': {'c': 13, 'g': {'h': 10, 'i': 16}, 'd': 14}, 'e': {'f': 10}}

在某些情况下，希望修改原始字典对象(以避免重新创建):

In some cases it's desired to modify the original dict object (to avoid re-creating it):

import collections

def map_nested_dicts_modify(ob, func):
    for k, v in ob.iteritems():
        if isinstance(v, collections.Mapping):
            map_nested_dicts_modify(v, func)
        else:
            ob[k] = func(v)

map_nested_dicts_modify(x, lambda v: v + 7)
# x is now
#    {'a': 8, 'b': {'c': 13, 'g': {'h': 10, 'i': 16}, 'd': 14}, 'e': {'f': 10}}

如果您使用的是Python 3:

If you're using Python 3:

• 将 dict.iteritems 替换为 dict.items

将import collections替换为import collections.abc

将collections.Mapping替换为collections.abc.Mapping

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